[pulseaudio-discuss] pulseaudio a2dp disconnect problem

Georg Chini georg at chini.tk
Sun Aug 16 04:40:42 PDT 2015


On 16.08.2015 13:26, Eytan Naim wrote:
>
> Hi Georg,
>
> It is asymmetric and I will explain.
>
> When a2dp connection is established, loopback_module is loaded- And 
> that is before streaming has started, so streaming is in IDLE state.
>
> Later, when remote device pauses the streaming for small interval, it 
> keeps the connection up, and I would expect PulseAudio state machine 
> would go back to an IDLE state- without removal of loppback_module.
>
> Thanks.
>
> *From:*pulseaudio-discuss 
> [mailto:pulseaudio-discuss-bounces at lists.freedesktop.org] *On Behalf 
> Of *Georg Chini
> *Sent:* Sunday, August 16, 2015 2:02 PM
> *To:* General PulseAudio Discussion
> *Subject:* Re: [pulseaudio-discuss] pulseaudio a2dp disconnect problem
>
> On 16.08.2015 12:26, Eytan Naim wrote:
>
>     Hi Tanu,
>
>     Thanks for your advice and cooperation.
>
>     As a result of the loopback_module asymmetric oddity, I compared
>     "pacmd list" output command between two states (you can see
>     attached files):
>
>     1.After connection establishment, and before streaming starts.
>
>     2.After streaming stops.
>
>     If the application would run normally I would expect to find
>     similar output. – but for some reason the Bluetooth card change
>     its active_profile from a2dp_sink to off, so, I assumed this may
>     be the problem.
>
>     So after digging a little bit in the code, I found a condition in
>     the ./src/modules/bluetooth/module-bluetooth-policy.c  that
>     include all profiles except mine(a2dp source).
>     So I decided to apply the following hunk, to prevent the card
>     changing its profile (it seemed reasonable for me, because all
>     other profile are included in this condition).
>
>     Do you know this Bluetooth code? Does it make sense? Is there
>     anyone I can ask to confirm it?
>
>     static pa_hook_result_t profile_available_hook_callback(pa_core
>     *c, pa_card_profile *profile, void *userdata) {
>
>     pa_card *card;
>
>         const char *s;
>
>         bool is_active_profile;
>
>     pa_card_profile *selected_profile;
>
>     pa_assert(c);
>
>     pa_assert(profile);
>
>     pa_assert_se((card = profile->card));
>
>         /* Only consider bluetooth cards */
>
>         s = pa_proplist_gets(card->proplist, PA_PROP_DEVICE_BUS);
>
>         if (!s || !pa_streq(s, "bluetooth"))
>
>     return PA_HOOK_OK;
>
>         /* Do not automatically switch profiles for headsets, just in
>     case */
>
>         /* TODO: remove a2dp and hsp when we remove BlueZ 4 support */
>
>         if (pa_streq(profile->name, "hsp") || pa_streq(profile->name,
>     "a2dp") || pa_streq(profile->name, "a2dp_sink") ||
>
>     -    pa_streq(profile->name, "a2dp_source") ||
>     pa_streq(profile->name, "headset_head_unit"))
>
>     + pa_streq(profile->name, "headset_head_unit")) {
>
>             return PA_HOOK_OK;
>
>>
>     It seemed it worked J, but the freezing issue still there L.
>
>     When an a2dp connection is lost, pa would freeze when trying to
>     reconnect and reload the Bluetooth modules.
>
>     gdb output:
>
>     (gdb) thread apply all bt
>
>     Thread 1 (process 1998):
>
>     #0  arm_modulus (p=1031, m=123328564) at
>     ./ldso/ldso/arm/dl-sysdep.h:29
>
>     #1  _dl_lookup_sysv_hash (type_class=<optimized out>,
>
>         undef_name=<optimized out>, hash=123328564, symtab=0xb6d0f3ec,
>
>         tpnt=0xb6fc5508) at ldso/ldso/dl-hash.c:255
>
>     #2  _dl_find_hash (
>
>         name=name at entry=0xbec1b5c0
>     "module_bluez5_device_LTX_pa__get_deprecated",
>
>         scope=<optimized out>, mytpnt=mytpnt at entry=0x0,
>
>     type_class=type_class at entry=-2147483648,
>     sym_ref=sym_ref at entry=0xbec1b558)
>
>         at ldso/ldso/dl-hash.c:339
>
>     #3  0xb6d86b1c in do_dlsym (caller_address=<optimized out>,
>
>         name=0xbec1b5c0 "module_bluez5_device_LTX_pa__get_deprecated",
>
>         vhandle=<optimized out>) at ldso/libdl/libdl.c:733
>
>     #4  dlsym (vhandle=<optimized out>,
>
>         name=0xbec1b5c0 "module_bluez5_device_LTX_pa__get_deprecated")
>
>         at ldso/libdl/libdl.c:765
>
>     #5  0x000116d8 in bind_now_find_sym (d=<optimized out>,
>     m=<optimized out>,
>
>         symbol=<optimized out>) at daemon/ltdl-bind-now.c:101
>
>     #6  0xb6e039b8 in lt_dlsym () from /usr/lib/libltdl.so.7
>
>     #7  0xb6f5b400 in pa_load_sym (handle=0x5e8f8,
>
>     module=module at entry=0xb686247a "module-bluez5-device",
>
>         symbol=0xb6fa3121 "pa__get_deprecated") at
>     pulsecore/ltdl-helper.c:42
>
>     ---Type <return> to continue, or q <return> to quit---
>
>     #8  0xb6f5d128 in pa_module_load (c=0x24f00,
>
>         name=0xb686247a "module-bluez5-device",
>
>         argument=argument at entry=0x5e2b0
>     "path=/org/bluez/hci0/dev_98_D6_F7_34_98_E8") at
>     pulsecore/module.c:151
>
>     #9  0xb6861ee0 in device_connection_changed_cb (y=<optimized out>,
>     d=0x50bb8,
>
>         u=0x38950) at modules/bluetooth/module-bluez5-discover.c:77
>
>     #10 0xb6f5b1a4 in pa_hook_fire (hook=0x37840, data=0x50bb8)
>
>         at pulsecore/hook-list.c:104
>
>     #11 0xb684f8cc in endpoint_set_configuration (m=m at entry=0x50f10,
>
>         userdata=userdata at entry=0x37830, conn=<optimized out>)
>
>         at modules/bluetooth/bluez5-util.c:1313
>
>     #12 0xb684fcdc in endpoint_handler (c=<optimized out>,
>     m=m at entry=0x50f10,
>
>         userdata=userdata at entry=0x37830) at
>     modules/bluetooth/bluez5-util.c:1517
>
>     #13 0xb6ddf800 in _dbus_object_tree_dispatch_and_unlock (tree=0x399e0,
>
>         message=message at entry=0x50f10,
>     found_object=found_object at entry=0xbec1b99c)
>
>         at dbus-object-tree.c:1018
>
>     #14 0xb6dd1104 in dbus_connection_dispatch (connection=0x39c28)
>
>         at dbus-connection.c:4718
>
>     #15 0xb6ec81b4 in dispatch_cb (ea=0x2124c, ev=0x35a20, userdata=0x407)
>
>         at pulsecore/dbus-util.c:53
>
>     #16 0xb6f1a798 in dispatch_defer (m=<optimized out>) at
>     pulse/mainloop.c:680
>
>     #17 pa_mainloop_dispatch (m=m at entry=0x21208) at pulse/mainloop.c:889
>
>     #18 0xb6f1ab98 in pa_mainloop_iterate (m=m at entry=0x21208,
>     block=block at entry=1,
>
>     ---Type <return> to continue, or q <return> to quit---
>
>         retval=retval at entry=0xbec1ba9c) at pulse/mainloop.c:929
>
>     #19 0xb6f1abfc in pa_mainloop_run (m=m at entry=0x21208,
>     retval=0xbec1ba9c,
>
>         retval at entry=0xbec1ba94) at pulse/mainloop.c:944
>
>     #20 0x0000d9ec in main (argc=<optimized out>, argv=<optimized out>)
>
>         at daemon/main.c:1134
>
>     -----Original Message-----
>     From: Tanu Kaskinen [mailto:tanuk at iki.fi]
>     Sent: Friday, August 14, 2015 12:00 PM
>     To: Eytan Naim; pulseaudio-discuss at lists.freedesktop.org
>     <mailto:pulseaudio-discuss at lists.freedesktop.org>
>     Subject: Re: [pulseaudio-discuss] pulseaudio a2dp disconnect problem
>
>     On Thu, 2015-08-13 at 12:35 +0000, Eytan Naim wrote:
>
>     > Hi Tanu,
>
>     >
>
>     > Thanks for the reply.
>
>     >
>
>     > I think that the loopback module shouldn’t be unloaded each time
>
>     > steaming stops for the simple reason that it is loaded when
>     connection
>
>     > is established, and not when streaming starts.
>
>     Yes, that's oddly asymmetric, and should perhaps be fixed. That
>     said, as long as module-loopback gets loaded again when the
>     streaming continues, the current logic shouldn't necessarily cause
>     too much trouble. In your case module-loopback doesn't get loaded
>     again, but that might be because pulseaudio gets stuck before that
>     has a chance to happen.
>
>     > I get all kind of PulseAudio problems, for example in the example
>
>     > below, PulseAudio success to stream in the start, but after pausing
>
>     > and playing again PulseAudio act differently.
>
>     >
>
>     > - It looks like PulseAudio has problem to handle changing
>     connection
>
>     > state or something.
>
>     >
>
>     >
>
>     >
>
>     > The below log was produced by the following steps:
>
>     >
>
>     > a)      connection establishment
>
>     >
>
>     > b)      streaming session
>
>     >
>
>     > c)       stop from remote device
>
>     >
>
>     > d)      unloading loopback module
>
>     >
>
>     > e)      toggling streaming start/stop without PulseAudio suitable
>
>     > response
>
>     >
>
>     > f)       pacmd failure for long time (more then 3-4 minutes). – so
>
>     > it’s probably not a dbus thing.
>
>     >
>
>     >
>
>     >
>
>     > Please notice that each time I try a test, something a little
>
>     > different happens- but it always has to do with modules
>
>     > unloading/PulseAudio doesn’t response
>
>     Getting stuck is the most interesting problem here. Can you run
>     pulseaudio in gdb, and when it gets stuck, stop and give command
>     "thread apply all bt"?
>
>     --
>
>     Tanu
>
>
> It is correct that the profile is set to "off" when a stream stops. 
> The a2dp connection
> is torn down on the bluetooth end, so it would not make sense to keep 
> the profile in
> pulesaudio. This is definitely not the cause of your problem. And 
> actually I cannot
> see that it's asymmetric. The loopback module is loaded as soon as the 
> profile is
> switched to a2dp and unloaded as soon as the profile changes to "off".
> BTW, you can avoid loading and unloading the loopback module 
> automatically by
> loading module-bluetooth-policy with argument a2dp_source=0. But then 
> you have
> to load the loopback manually and move it to the right source. Maybe 
> it is a good idea
> to test that because the issue might also be caused by 
> module-bluetooth-policy.
>
> The phone application I wrote handles insertion of loopback modues and 
> does not
> rely on module-bluetuetooth policy for that. Up to now I have not seen 
> a similar
> issue, the application reacts to switches between a2dp/hsp/off without 
> problems.
>
> Georg
>
>
Hi,
my main point was that you should test it with a2dp_source=0 as
argument to module-bluetooth-policy, because I am using it that
way and it works without issues. It might help to narrow down the
problem.
I won't argue about the symmetry.

Regards
              Georg
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